On-board sensor cleaning apparatus and on-board sensor cleaning method

ABSTRACT

The on-board sensor cleaning apparatus is applied to a vehicle having a front camera, a rear camera, a center display, and an electronic inner mirror. A surrounding image obtained through the front camera and the rear camera is displayed on the center display and the electronic inner mirror. The on-board sensor cleaning apparatus includes an ECU, a position information obtaining device, and a cleaning unit. The ECU obtains a visual check probability for an area which includes a position of the vehicle indicated by vehicle position information, from a database. The ECU sets an automatic cleaning start condition based on the obtained visual check probability.

TECHNICAL FIELD

The present disclosure relates to an on-board sensor cleaning apparatusconfigured to clean a detecting surface part of an on-board sensor withcleaning fluid, the detecting surface part being a part through which asignal (e.g., electromagnetic wave such as visible light, laser light,infrared light, and electrical wave in millimeter waveband, and sonicwave) passes, wherein the signal is received by the on-board sensor.

BACKGROUND

Conventionally, a vehicle (host vehicle) equipped with an apparatus toassist a driver of the vehicle in easily monitoring surroundings of thevehicle has been known.

In one example of such a vehicle, an image of the surroundings of thevehicle acquired by a camera sensor serving as an on-board sensor isdisplayed on a display device. In another example of such a vehicle,surroundings monitoring assist information (e.g., information indicatingthat another vehicle is approaching the host vehicle) is displayed on adisplay device. The surroundings monitoring assist information isacquired by an on-board sensor such as a radar sensor, and an ultrasonicsound wave sensor.

Japanese Patent Application Laid-Open No. 2019-123262 discloses anon-board sensor cleaning apparatus (referred to as a “conventionalapparatus”) configured to clean a detecting surface part of an on-boardsensor with cleaning fluid at regular intervals (i.e., an on-boardsensor cleaning apparatus configured to execute an automatic cleaning(process) at regular intervals).

SUMMARY

When the on-board sensor is the camera sensor, the image of thesurroundings of the vehicle acquired by the camera sensor may becomeblurred while the automatic cleaning is being executed, because thecleaning fluid is included in the image. When the on-board sensor is asensor other than the camera sensor, detection accuracy of the on-boardsensor is degraded due to the cleaning fluid used to clean the detectingsurface part of the on-board sensor while the automatic cleaning isbeing executed, and thus, there may be a case where the surroundingsmonitoring assist information is inaccurate. Therefore, when the vehicleis in a position/location where the driver tends/needs to watch (look ator visually check) at least one of the surrounding image and thesurroundings monitoring assist information, it is preferable that theautomatic cleaning is not executed as much as possible.

However, as described above, the conventional apparatus executes theautomatic cleaning at regular intervals. Accordingly, the conventionalapparatus has a high possibility of executing the automatic cleaningwhen the vehicle is at the position/location where the drivertends/needs to watch at least one of the surrounding image and thesurroundings monitoring assist information.

The present disclosure is made to cope with the problem described above.One of objectives of the present disclosure is to provide an on-boardsensor cleaning apparatus (and an on-board sensor cleaning method) thathas a low possibility of executing an automatic cleaning (process) ofthe on-board sensor, when the vehicle is at the position/location wherethe driver tends/needs to watch at least one of “an image andinformation” acquired using the on-board sensor. Hereinafter, theon-board sensor cleaning apparatus according to the present disclosuremay sometimes be referred to as a “present disclosure cleaningapparatus”, and the on-board sensor cleaning method according to thepresent disclosure may sometimes be referred to as a “present disclosurecleaning method.”

The present disclosure cleaning apparatus is applied to a vehicle (SV).The vehicle (SV) includes an on-board sensor (11, 12) configured toobtain information representing surroundings of the vehicle based onelectromagnetic wave or sonic wave which passes through a detectingsurface part exposed to outside of the vehicle (SV), and a displaydevice (20, 30) configured to display an image or displayed informationproduced based on the information obtained by the on-board sensor.

The present disclosure cleaning apparatus comprises:

a cleaning unit (U1) configured to perform a cleaning process to cleanthe detecting surface part of the on-board sensor using cleaning fluid;

a position information obtaining device (14) configured to obtainvehicle position information indicating a position of the vehicle; and

a control unit (10) configured to:

-   -   obtain a result of a determination of whether or not an        automatic cleaning start condition is satisfied (steps 505 to        530), wherein the determination is made, using a storage device        (60, 102) which has stored a piece of area position information        capable of identifying a position of each of predetermined areas        on a ground and a visual check probability correlating value        correlated with a visual check probability that a driver of the        vehicle visually checks the display device while the piece of        area position information and the visual check probability        correlating value being associated with each other, based on the        visual check probability correlating value which corresponds to        one of the areas which includes the position of the vehicle        indicated by the vehicle position information obtained by the        position information obtaining device; and    -   control the cleaning unit in such a manner that the cleaning        unit performs the cleaning process (step 535) when the result of        the determination indicates that the automatic cleaning start        condition is satisfied (“Yes” determination at step 530).

The present disclosure cleaning apparatus executes the cleaning processwhen the result of the determination as to whether or not the automaticcleaning start condition is satisfied indicates that the automaticcleaning start condition is satisfied. The automatic cleaning startcondition is set/varied based on the visual check probabilitycorrelating value corresponding to the present position of the vehicle.Therefore, the present disclosure cleaning apparatus can decrease afrequency (possibility) of executing the automatic cleaning of theon-board sensor, when the vehicle is at the position where the drivertends/needs to watch at least one of “the image and the displayedinformation” produced using the on-board sensor.

In one of the embodiments of the present disclosure cleaning apparatusfurther comprises the storage device (60) mounted on the vehicle.

In this embodiment, the control unit is configured to:

-   -   obtain, based on the obtained vehicle position information, the        visual check probability correlating value corresponding to one        of the areas which includes the position of the vehicle, from        the storage device (step 505-step 515);    -   set the automatic cleaning start condition based on the obtained        visual check probability correlating value (step 520); and    -   determine whether or not the automatic cleaning start condition        becomes satisfied (step 530) so as to obtain the result of the        determination.

According to the above-described embodiment, the automatic cleaningstart condition is set/determined based on the visual check probabilitycorrelating value obtained from the storage device mounted on thevehicle. Thus, it becomes unlikely that the automatic cleaning for theon-board sensor is executed, when the vehicle is at the position wherethe driver tends/needs to watch at least one of “the image and thedisplayed information” produced using the on-board sensor.

One of the embodiments of the present disclosure cleaning apparatusfurther comprises a radio communication device (110) which is mounted onthe vehicle and is configured to be capable of communicating with aninformation-processing equipment which is located outside of the vehicleand which includes the storage device (102).

In this embodiment, the control unit is configured to:

-   -   obtain, based on the obtained vehicle position information, the        visual check probability correlating value corresponding to one        of the areas which includes the position of the vehicle, from        the storage device, by communicating with the        information-processing equipment using the radio communication        device; and    -   obtain the result of the determination, by setting the automatic        cleaning start condition based on the obtained visual check        probability correlating value, and by determining whether or not        the automatic cleaning start condition becomes satisfied.

According to the above-described embodiment, the automatic cleaningstart condition is set/determined based on the visual check probabilitycorrelating value obtained from the storage device located outside ofthe vehicle through the radio communication device. Thus, it becomesunlikely that the automatic cleaning for the on-board sensor isexecuted, when the vehicle is at the position where the drivertends/needs to watch at least one of “the image and the displayedinformation” produced using the on-board sensor.

In one of the embodiments of the present disclosure cleaning apparatus,the on-board sensor is a camera sensor (11, 12) which is configured totake a picture of the surroundings of the vehicle using light as theelectromagnetic wave to obtain image information as the informationrepresenting the surroundings of the vehicle.

In this case, the control unit is configured to:

-   -   obtain, based on the image information, a dirty degree        indicating value indicating a degree of dirtiness of the        detecting surface part of the on-board sensor; and    -   determine whether or not the automatic cleaning start condition        becomes satisfied by comparing the dirty degree indicating value        and a cleaning threshold (step 530),    -   set the cleaning threshold based on the obtained visual check        probability correlating value so as to set the automatic        cleaning start condition (step 520); and    -   obtain the result of the determination which is indicating that        the automatic cleaning start condition has become satisfied when        the dirty degree indicating value is larger than the cleaning        threshold (“Yes” determination at step 530).

According to the above-described embodiment, the cleaning threshold thatis to be compared with the dirty degree indicating value isdetermined/varied based on the visual check probability correlatingvalue. Thus, the automatic cleaning start condition can be set inaccordance with the visual check probability. Accordingly, it becomesunlikely that the automatic cleaning for the on-board sensor isexecuted, when the vehicle is at the position where the drivertends/needs to watch at least one of “the image and the displayedinformation” produced using the on-board sensor.

In one of the embodiments of the present disclosure cleaning apparatus,the control unit is configured to vary the cleaning threshold in such amanner that the cleaning threshold is greater when the obtained visualcheck probability correlating value is a specific value than when theobtained visual check probability correlating value is smaller than thespecific value, so as to set the automatic cleaning start condition(step 520).

According to the above-described embodiment, since the cleaningthreshold which is to be compared with the dirty degree indicating valueis determined/varied in the manner described above, the automaticcleaning start condition is harder to be satisfied as the visual checkprobability correlating value is greater. Accordingly, it becomesunlikely that the automatic cleaning for the on-board sensor isexecuted, when the vehicle is at the position where the drivertends/needs to watch at least one of “the image and the displayedinformation” produced using the on-board sensor.

In one of the embodiments of the present disclosure cleaning apparatus,the control unit is configured to vary the cleaning threshold (step1015) so as to set the automatic cleaning start condition in such amanner that:

-   -   the cleaning threshold is equal to a first threshold when the        obtained visual check probability correlating value is in a        first range that is equal to or smaller than a first visual        check probability correlating value; and    -   the cleaning threshold is equal to a second threshold smaller        than the first threshold when the obtained visual check        probability correlating value is in a second range that is        larger than the first visual check probability correlating value        and smaller than a second visual check probability correlating        value, and a change in the visual check probability correlating        value indicates a tendency that the visual check probability        correlating value is increasing (“Yes” determination at step        1010).

According to the above-described embodiment, the cleaning thresholdwhich is to be compared with the dirty degree indicating value isdetermined/varied in the manner described above. Accordingly, a consumedamount of the cleaning fluid can be reduced. In addition, it can beeasier for the automatic cleaning to be executed before the vehiclereaches an area where the visual check probability correlating value isvery high.

One of the embodiments of the present disclosure cleaning apparatusfurther comprises a driver's information obtaining device (13)configured to obtain driver's information that is used for determining astate of the driver.

In this case, the control unit is configured to prohibit executing thecleaning process while it is determined, based on the driver'sinformation, that the driver is visually checking the display device(“No” determination at step 1205, step 1210, step 1215, and “No”determination at step 530).

According to the above-described embodiment, the automatic cleaning canbe surely prevented from being executed while the driver is looking atleast one of “the image and the displayed information” produced usingthe on-board sensor.

One of the embodiments of the present disclosure cleaning apparatusfurther comprises a driver's information obtaining device configured toobtain driver's information that is used for determining a state of thedriver.

In this case, the control unit is configured to:

-   -   make a visually-check-determination as to whether or not the        driver has visually checked the display device, based on the        driver's information (step 310);    -   identify one of the areas that includes a position at which a        result of the visually-check-determination is obtained (step        410);    -   calculate the visual check probability correlating value for the        identified one of the areas, based on the result of the        visually-check-determination (step 425-step 445); and    -   store the calculated visual check probability correlating value        in the storage device while associating the calculated visual        check probability correlating value with the area position        information indicating the identified one of the areas (step        450).

According to the above-described embodiment, thevisually-check-determination as to whether or not the driver hasvisually checked the display device in the area where the vehicle hasactually traveled is made, and the calculated visual check probabilitycorrelating value calculated based on the result of thevisually-check-determination is stored in the storage device. Therefore,the above-described embodiment can store the visual check probabilitycorrelating value with high accuracy in the storage device.

The present disclosure cleaning method is applied to a vehicle (SV) thatincludes:

an on-board sensor (11, 12) configured to obtain informationrepresenting surroundings of the vehicle based on electromagnetic waveor sonic wave which passes through a detecting surface part exposed tooutside of the vehicle;

a display device (20, 40) configured to display an image or displayedinformation produced based on the information obtained by the on-boardsensor;

a cleaning unit (U1) configured to perform a cleaning process to cleanthe detecting surface part of the on-board sensor using cleaning fluid;and

a position information obtaining device (14) configured to obtainvehicle position information indicating a position of the vehicle.

The present disclosure cleaning method comprises:

a step (step 515) of obtaining a visual check probability correlatingvalue corresponding to one of areas which includes a position of thevehicle indicated by the vehicle position information, using a storagedevice (60) which has stored a piece of area position informationcapable of identifying a position of each of predetermined areas on aground and a visual check probability correlating value correlated witha visual check probability that a driver of the vehicle visually checksthe display device while the piece of area position information and thevisual check probability correlating value being associated with eachother;

a step (step 520) of setting an automatic cleaning start condition basedon the obtained visual check probability correlating value;

a step (step 530) of obtaining a result of a determination of whether ornot the automatic cleaning start condition becomes satisfied; and

a step (step 535) of controlling the cleaning unit in such a manner thatthe cleaning performs the cleaning process when the result of thedetermination indicates that the automatic cleaning start condition issatisfied (“Yes” determination at step 530).

According to the present disclosure cleaning method, the cleaningprocess is executed when the result of the determination as to whetheror not the automatic cleaning start condition is satisfied indicatesthat the automatic cleaning start condition is satisfied. The automaticcleaning start condition is set/varied based on the visual checkprobability correlating value corresponding to the present position ofthe vehicle. Therefore, the present disclosure cleaning method candecrease a frequency (possibility) of executing the automatic cleaningof the on-board sensor, when the vehicle is at the position where thedriver tends/needs to watch at least one of “the image and the displayedinformation” produced using the on-board sensor.

One of the embodiments of the present disclosure cleaning method furtherincludes:

a step (step 305, step 310) of obtaining driver's information that isused for determining a state of the driver;

a step (step 310) of making a determination as to whether or not thedriver has visually checked the display device, based on the driver'sinformation, and of (step 410) identifying one of the areas thatincludes a position at which a result of the determination is obtained;

a step (step 425-step 445) of calculating the visual check probabilitycorrelating value for the identified one of the areas, based on theresult of the determination; and

a step (step 450) of storing the calculated visual check probabilitycorrelating value in the storage device while associating the calculatedvisual check probability correlating value with the area positioninformation indicating the identified one of the areas.

According to the above-described embodiment, thevisually-check-determination as to whether or not the driver hasvisually checked the display device in the area where the vehicle hasactually traveled is made, and the calculated visual check probabilitycorrelating value calculated based on the result of thevisually-check-determination is stored in the storage device. Therefore,the above-described embodiment can store the visual check probabilitycorrelating value with high accuracy in the storage device.

Notably, in the above description, in order to facilitate understandingof the present disclosure, the constituent elements or the like of thedisclosure corresponding to those of the embodiments of the disclosurewhich will be described later are accompanied by parenthesized namesand/or symbols which are used in the embodiments. However, theconstituent elements of the disclosure are not limited to those in theembodiments defined by the names and/or the symbols.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an on-board apparatus including a firstcleaning apparatus according to an embodiment of the present disclosure.

FIG. 2 is a top view of a road.

FIG. 3 is a flowchart showing a routine executed by a CPU of an ECU ofeach of the first to a third cleaning apparatus.

FIG. 4 is a flowchart showing a routine executed by the CPU of the ECUof each of the first to the third cleaning apparatus.

FIG. 5 is a flowchart showing a routine executed by the CPU of the ECUof the first cleaning apparatus.

FIG. 6 is a figure for describing an outline of operations of the firstcleaning apparatus.

FIG. 7 is a flowchart showing a routine executed by a CPU of an ECU of amodification of the first cleaning apparatus.

FIG. 8 is a flowchart showing a routine executed by the CPU of the ECUof the modification of the first cleaning apparatus.

FIG. 9A is a figure for describing a second map Map2.

FIG. 9B is a figure for describing a third map Map3.

FIG. 10 is a flowchart showing a routine executed by the CPU of the ECUof the second cleaning apparatus.

FIG. 11 is a figure for describing an outline of operations of thesecond cleaning apparatus.

FIG. 12 is a flowchart showing a routine executed by the CPU of the ECUof the third cleaning apparatus.

FIG. 13 is a figure for describing an outline of operations of the thirdcleaning apparatus.

FIG. 14 is a schematic diagram of an on-board sensor cleaning systemaccording to an embodiment of the present disclosure.

DETAILED DESCRIPTION First Embodiment <Configuration>

As shown in FIG. 1, an on-board apparatus including an on-board sensorcleaning apparatus (hereinafter, sometimes referred to as a “firstcleaning apparatus”) according to a first embodiment of the presentdisclosure is mounted on a vehicle SV. The on-board apparatus comprisesan ECU 10, a front camera 11, a rear camera 12, a driver monitoringcamera 13, a position information obtaining device 14, a center display20, an electronic inner mirror 30, a cleaning (washing) unit U1, and astorage device 60. The cleaning unit U1 includes a tank TA1, a firstpump 40, a first nozzle 41, a second pump 50, and a second nozzle 51.The first cleaning apparatus includes the ECU 10, the driver monitoringcamera 13, the position information obtaining device 14, the cleaningunit U1, and the storage device 60.

The ECU 10 is an electronic control unit that includes a microcomputeras a main component, and is sometimes referred to as a controller. Themicrocomputer includes a CPU, a ROM, a RAM, and an interface (I/F). TheCPU is configured and/or programmed to realize various functions byexecuting instructions (or programs, or routines) stored in the ROM. TheECU 10 may be implemented by a plurality of ECUs.

The ECU 10 is connected to the front camera 11, the rear camera 12, thedriver monitoring camera 13, and the position information obtainingdevice 14. Hereinafter, when the front camera 11 and the rear camera 12need not be distinguished from each other, each of them is sometimesreferred to as a “camera sensor (or a surroundings camera device)”.

The front camera 11 is disposed at a center of a front end part of thevehicle SV. The front camera 11 is one of on-board sensors, and has adetecting surface part (detecting surface section) that is exposed tothe outside of the vehicle SV. The front camera 11 includes a lightreceiving element. Visible light from an area in front of the vehicle SVcorresponding to a shooting range of the front camera 11 is led to thelight receiving element. The front camera 11 obtains (captures) imageinformation (front image data) representing the area (scene) in front ofthe vehicle SV using the light receiving element. The front camera 11transmits the obtained image information to the ECU 10. The ECU 10produces a frontward surrounding image including an image correspondingto the shooting range, based on the image information that the ECU 10receives. The frontward surrounding image functions as an image thatassists the driver of the vehicle SV in monitoring the area (front area)in front/ahead of the vehicle SV.

The rear camera 12 is disposed at a center of a rear end part of thevehicle SV. The rear camera 12 is one of the on-board sensors, and has adetecting surface part (detecting surface section) that is exposed tothe outside of the vehicle SV. The rear camera 12 includes a lightreceiving element. Visible light from an area in the rear of the vehicleSV corresponding to a shooting range of the rear camera 12 is led to thelight receiving element. The rear camera 12 obtains (captures) imageinformation (rear image data) representing the area (scene) in the rearof the vehicle SV using the light receiving element. The rear camera 12transmits the obtained image information to the ECU 10. The ECU 10produces a rearward surrounding image including an image correspondingto the shooting range, based on the image information that the ECU 10receives. The rearward surrounding image functions as an image thatassists the driver of the vehicle SV in monitoring the area (rear area)in the rear of the vehicle SV. When the front surrounding image and therearward surrounding image need not to be distinguished from each other,each of them is sometimes referred to as a “surrounding image.”

The driver monitoring camera 13 is disposed at a position from where thedriver monitoring camera 13 can take a picture of a face of the driversitting in a driver's seat of the vehicle SV. The driver monitoringcamera 13 photographs a face of the driver that is present in itsshooting range so as to produce a driver's image. The driver monitoringcamera 13 transmits the obtained driver's image to the ECU 10. The ECU10 produces/obtains a driver's information (e.g., information indicativeof a driver's line of sight (driver's eye direction)) used to determinea state of the driver, based on the driver's image transmitted from thedriver monitoring camera 13. The driver monitoring camera 13 issometimes referred to as a “driver's information obtaining device”, forconvenience sake.

The position information obtaining device 14 includes a GNSS (GlobalNavigation Satellite System) receiver. The GNSS receiver receivessignals (i.e., GNSS signals) transmitted from satellites included in theGNSS system for detecting a present/current position/location(hereinafter, referred to as a “present position”) of the vehicle SV atthe present time point. The position information obtaining device 14obtains position information indicative of the present position of thevehicle SV. It should be noted that a position is represented(expressed) by latitude and longitude, for instance. The positioninformation obtaining device 14 transmits the thus obtained positioninformation to the ECU 10.

The ECU 10 is further connected to the center display 20, the electronicinner mirror 30, the first pump 40, the second pump 50, and the storagedevice 60.

The center display 20 is a touch panel screen that can display an image.The center display 20 is disposed in the vicinity of a center in avehicle width direction of an unillustrated instrumental panel in acabin of the vehicle SV. The ECU 10 displays the frontward surroundingimage and/or the rearward surrounding image on the center display 20.

The electronic inner mirror 30 includes a monitor section (an innermirror display) 31 configured to display an image. The monitor section31 is disposed at a position such that the driver can look at themonitor section 31. For example, the monitor section 31 is disposed at acenter upper position of a front windshield in the side of the cabin,the position at which a conventional inner mirror is disposed. The ECU10 displays the rearward surrounding image on the monitor section 31 ofthe electronic inner mirror 30.

The first pump 40 is communicated with the tank TA1 via a fluid pipeCL1. The tank TA1 is a reservoir storing cleaning fluid. The first pump40 is communicated with the first nozzle 41 via the fluid pipe CL1. Thefirst nozzle 41 is disposed at a position from which the first nozzle 41can inject the cleaning fluid toward the detecting surface part of thefront camera 11.

A driving state of the first pump 40 is controlled by the ECU 10. Whenthe first pump 40 is driven by the ECU 10, the first pump 40 sucks inthe cleaning fluid through the fluid pipe CL1 and supplies the cleaningfluid to the first nozzle 41 so that the first nozzle 41 injects thecleaning fluid supplied from the tank TA1 to/toward the detectingsurface part of the front camera 11. Namely, the ECU 10 can drive thefirst pump 40 to clean/wash the detecting surface part of the frontcamera 11.

The second pump 50 is communicated with the tank TA1 via the fluid pipeCL1. The second pump 50 is communicated with the second nozzle 51 viathe fluid pipe CL1. The second nozzle 51 is disposed at a position fromwhich the second nozzle 51 can inject the cleaning fluid toward thedetecting surface part of the rear camera 12.

A driving state of the second pump 50 is controlled by the ECU 10. Whenthe second pump 50 is driven by the ECU 10, the second pump 50 sucks inthe cleaning fluid through the fluid pipe CL1 and supplies the cleaningfluid to the second nozzle 51 so that the second nozzle 51 injects thecleaning fluid supplied from the tank TA1 to/toward the detectingsurface part of the rear camera 12. Namely, the ECU 10 can drive thesecond pump 50 to clean/wash the detecting surface part of the rearcamera 12.

The storage device 60 is a non-volatile readable and writablestorage/memory device (in the present example, a hard disc) configuredsuch that data can be written into the storage device 60 and data can beread out from the storage device 60. The ECU 10 can store information inthe storage device 60, and read information stored in the storage device60 out from the storage device 60. The storage device 60 includes a mapinformation database 60 a and a visual check probability database (orvisible contact probability database) 60 b.

The map information database 60 a has stored map information. The mapinformation includes position information representing a position ofeach road (position information for each lane) and information toidentify a shape of each road. The map information also includesinformation representing a width of each road, position information oneach parking lot, each intersection, each road fork, and each trafficlight.

In the visual check probability database 60 b, area position informationwhich identifies/specifies each position of “a plurality of areas ARj,described later” is stored. In addition, “a visual check probability (orvisible contact probability) Prj, an accumulated number of confirmationsNCj, and an accumulated number of determinations NDj” associated witheach of the areas ARj are also stored in the visual check probabilitydatabase 60 b.

As shown in FIG. 2, a road(s) Ro1 on which the vehicle SV can travel, anunillustrated parking lot(s), and the like are divided in a plurality ofthe areas ARj, based on the map information. The area positioninformation is position information that identifies/indicates a positionof each of the areas ARj. The area ARj has a predetermined size and apredetermined shape (in the present example, a square shape). The areaposition information identifying the area ARj includes a “set of fourpieces of position information” that identifies, using latitude andlongitude, positions (Parj1, Parj2, Parj3, Parj4) of four vertexes ofthe square having the predetermined size corresponding to the area ARj,for instance.

The visual check probability Prj is a probability (visible check/contactprobability) that the driver of the vehicle SV looks at (visuallychecks) at least one of the center display 20 and the electronic innermirror 30, in the area ARj. The visual check probability Prj may bereferred to as a “visual check probability correlating value” that iscorrelated with the visual check probability, and is larger as thevisible check probability is higher. It should be noted that,hereinafter, when the center display 20 and the electronic inner mirror30 need not to be distinguished from each other, each of them isreferred to as a “display (display screen)” that is also sometimesreferred to as a “display device” for convenience sake.

The accumulated number of confirmations NCj is an accumulated value(hereinafter, sometimes referred to as the “cumulative number”) of timesof a case where it is determined that the driver of the vehicle SV haslooked at (visually checked) the display at least once while the vehicleSV passes through the area ARj. The accumulated number of determinationsNDj is an accumulated value of times of a case where it is determinedthat the vehicle SV passed through the area ARj. In other words, theaccumulated number of determinations NDj is an accumulated value of acase where the determination as to whether or not the driver of thevehicle SV has looked at (visually checked) the display at least once inthe area ARj is made. It should be noted that initial values of theaccumulated number of confirmations NCj and the accumulated number ofdeterminations NDj are both set at “0”. The visual check probability Prjis calculated by dividing the accumulated number of confirmations NCj bythe accumulated number of determinations NDj (i.e., Prj=NCj/NDj).

<Outline of Cleaning Process>

The ECU 10 executes an automatic cleaning process for automaticallycleaning/washing the detecting surface part of the front camera 11, whenthe ECU 10 determines that the detecting surface part of the frontcamera 11 has become dirty. Similarly, the ECU 10 executes an automaticcleaning process for automatically cleaning/washing the detectingsurface part of the rear camera 12, when the ECU 10 determines that thedetecting surface part of the rear camera 12 has become dirty.

More specifically, the ECU 10 obtains (detects) an index/indicatingvalue (hereinafter, simply referred to as a “dirty degree indicatingvalue”) that indicates a degree of dirtiness of each of the detectingsurface part of the front camera 11 and the detecting surface part ofthe rear camera 12. The ECU 10 obtains the dirty degree indicating valueof the front camera 11 based on the frontward surrounding image, andobtains the dirty degree indicating value of the rear camera 12 based onthe rearward surrounding image, as follows.

The dirty degree indicating value of the front camera 11 is a ratioexpressed in percentage of an area of dirty portions in the frontwardsurrounding image to an entire area of the frontward surrounding image.Namely, the dirty degree indicating value of the front camera 11 is asfollows.

The dirty degree indicating value of the front camera 11=100·[(area ofdirty portions in the frontward surrounding image)/(entire area of thefrontward surrounding image)]

The dirty portion in the frontward surrounding image is a “portion(region) of the frontward surrounding image” where a change in itsluminance continues being equal to or smaller than a threshold for apredetermined time or longer. In other words, the dirty portion in thefrontward surrounding image is a portion (region) having the luminancethat does not substantially change in a plurality of the successivefrontward surrounding images.

The dirty degree indicating value of the rear camera 12 is a ratioexpressed in percentage of an area of dirty portions in the rearwardsurrounding image to an entire area of the rearward surrounding image.Namely, the dirty degree indicating value of the rear camera 12 is asfollows.

The dirty degree indicating value of the rear camera 12=100·[(area ofdirty portions in the rearward surrounding image)/(entire area of therearward surrounding image)]

The dirty portion in the rearward surrounding image is a “portion(region) of the rearward surrounding image” where a change in itsluminance continues being equal to or smaller than a threshold for apredetermined time or longer. In other words, the dirty portion in therearward surrounding image is a portion (region) having the luminancethat does not substantially change in a plurality of the successiverearward surrounding images.

As is apparent from the above, the dirty degree indicating value becomesgreater as a proportion of the dirty portions in the image displayed onthe display becomes higher.

The ECU 10 monitors (continue determining) whether or not an automaticcleaning start condition for the front camera 11 (hereinafter, thecondition being referred to as a “Fr automatic cleaning startcondition”) becomes satisfied. The Fr automatic cleaning start conditionbecomes satisfied when the dirty degree indicating value of the frontcamera 11 becomes greater than a cleaning threshold thFr. When the ECU10 determines that the Fr automatic cleaning start condition becomessatisfied, the ECU 10 start to drive the first pump 40 for apredetermined time length (first time length) to inject a predeterminedamount of the cleaning fluid from the first nozzle 41 so as to clean(execute an automatic clean process for) the detecting surface part ofthe front camera 11.

The ECU 10 monitors (continue determining) whether or not an automaticcleaning start condition for the rear camera 12 (hereinafter, thecondition being referred to as a “Rr automatic cleaning startcondition”) becomes satisfied. The Rr automatic cleaning start conditionbecomes satisfied when the dirty degree indicating value of the rearcamera 12 becomes greater than a cleaning threshold thRr. When the ECU10 determines that the Rr automatic cleaning start condition becomessatisfied, the ECU 10 start to drive the second pump 50 for apredetermined time length (second time length) to inject a predeterminedamount of the cleaning fluid from the second nozzle 51 so as to clean(execute an automatic clean process for) the detecting surface part ofthe rear camera 12.

It should be noted that the cleaning threshold thFr and the cleaningthreshold thRr are equal to each other, in the present example. Each ofthe cleaning threshold thFr and the cleaning threshold thRr is referredto as a “cleaning threshold th”, hereinafter. Furthermore, each of theFr automatic cleaning start condition and the Rr automatic cleaningstart condition may be simply referred to as a “cleaning startcondition”, hereinafter. The cleaning threshold thFr and the cleaningthreshold thRr may be different from each other. The first time lengthand the second time length are equal to each other, but may be differentfrom each other.

<Outline of Operation>

While the automatic clean process for the detecting surface part of thefront camera 11 is being executed, the cleaning fluid is injected to thedetecting surface part of the front camera 11 so that the frontwardsurrounding image becomes blurred (unclear). When this happens, thedriver may not be able to monitor the area in front of the vehicle SV byvisually checking (looking at) the frontward surrounding image.Likewise, while the automatic clean process for the detecting surfacepart of the rear camera 12 is being executed, the cleaning fluid isinjected to the detecting surface part of the rear camera 12 so that therearward surrounding image becomes blurred (unclear). When this happens,the driver may not be able to monitor the area in the rear of thevehicle SV by visually checking (looking at) the rearward surroundingimage.

In view of the above, it is preferable that the automatic clean processfor the front camera 11 and the automatic clean process for the rearcamera 12 be executed while the vehicle is located in an area ARj wherethere is a low possibility or a low need that the driver visually checks(looks at) the display in order to monitor the surroundings (the frontarea and/or the rear area) of the vehicle SV

Meanwhile, it can be said that a “possibility that the driver visuallychecks the display (i.e., the surrounding image) in order to monitor thesurroundings when the vehicle SV is in the area ARj” is lower, as thevisual check probability Prj of that area ARj is lower. In other words,it can be said that a “possibility that the driver visually checks thedisplay (i.e., the surrounding image) in order to monitor thesurroundings when the vehicle SV is in the area ARj” is higher, as thevisual check probability Prj of that area ARj is higher.

In view of the above, the first cleaning apparatus varies the cleaningthreshold th in such a manner that the cleaning threshold th is smaller,as the visual check probability Prj of the area ARj in which the vehicleis located is lower. In other words, the first cleaning apparatus variesthe cleaning threshold th in such a manner that the cleaning thresholdth is larger, as the visual check probability Prj of the area ARj inwhich the vehicle is located/positioned is higher.

Accordingly, in the first cleaning apparatus, the cleaning startcondition becomes satisfied more easily (i.e., the cleaning threshold this smaller), as the visual check probability Prj of the area ARj inwhich the vehicle is located is lower. Therefore, a possibility that theautomatic cleaning is executed is higher, when the vehicle SV is locatedin an area where a possibility that the driver visually checks (looksat) the surrounding image displayed on the display is relatively low.

Whereas, in the first cleaning apparatus, the cleaning start conditionbecomes satisfied more rarely (or harder to be satisfied) (i.e., thecleaning threshold th is larger), as the visual check probability Prj ofthe area ARj in which the vehicle is located/positioned is higher.Therefore, a possibility that the automatic cleaning is not executed ishigher, when the vehicle SV is located in an area where a possibilitythat the driver visually checks (looks at) the surrounding imagedisplayed on the display is relatively high.

<Specific Operation>

The CPU (hereinafter, simply referred to as the “CPU”) of the ECU 10executes each of routines shown by flowcharts in FIGS. 3 to 5, everytime a predetermined time elapses.

Accordingly, when an appropriate time comes, the CPU starts process ofstep 300 shown in FIG. 3, and proceeds to step 305. At step 305, the CPUobtains the driver's image from the driver monitoring camera 13, andobtains, from the position information obtaining device 14, the positioninformation of the vehicle SV that was obtained when the driver's imagewas obtained by the driver monitoring camera 13.

Subsequently, the CPU proceeds to step 310 so as obtain, based on thedriver's image, the driver's information (i.e., the informationindicative of the driver's line of sight). Thereafter, the CPUdetermines, based on the thus obtained driver's line of sight, whetheror not the driver is looking at (i.e., visually checking, or is invisual contact with) the display. More specifically, the CPU determineswhether or not the driver's line of sight is directed in the directionof either the center display 20 or the electronic inner mirror 30. TheCPU determines that the driver is looking at the display, when it isdetermined that the driver's line of sight is directed in the directionof either the center display 20 or the electronic inner mirror 30.

When the driver is looking at the display, the CPU makes a “Yes”determination at step 310, and proceeds to step 315 so as to set a valueof a confirmation flag Xf at “1”. When the value of the confirmationflag Xf is “1”, the confirmation flag Xf indicates that the driver islooking at the display. When the value of the confirmation flag Xf is“0”, the confirmation flag Xf indicates that the driver is not lookingat the display. The value of the confirmation flag Xf is set to “0”through an initialization routine executed by the CPU when anunillustrated ignition key switch of the vehicle SV is changed from anoff position to an on position. Furthermore, as described later, thevalue of the confirmation flag Xf is set to “0” when the position of thevehicle SV has changed from an Area ARj-1 to an area ARj (refer to step435 shown in FIG. 4). Thereafter, the CPU proceeds to step 320.

Whereas, when the driver is not looking at the display, the CPU makes a“No” determination at step 310, and directly proceeds to step 320

At step 320, the CPU associate/correlates the value of the confirmationflag Xf with the position information obtained at step 305, and storesthem in the RAM. Thereafter, the CPU proceeds to step 395 so as toterminate the present routine.

The CPU starts process of step 400 shown in FIG. 4 after executing theroutine shown in FIG. 3, and sequentially executes “processes of step405 and step 410” described below so as to proceed to step 415.

Step 405: the CPU reads out “the position information and the value ofthe confirmation flag Xf” stored in the RAM at step 320.

Step 410: the CPU identifies/specifies the area ARj that includes aposition indicated by the position information obtained at step 405 bysearching the visual check probability database 60 b. In other words,the CPU identifies/specifies the area ARj that includes the position atwhich the vehicle SV is currently present and which is the position ofthe vehicle SV at the time point at which the driver's image wasobtained.

At step 415, the CPU determines whether or not the area ARj identifiedat step 410 (i.e., the present area ARj) is different from a previousarea ARj-1 that is the area ARj that was identified when the presentroutine was executed the predetermined time before. In other words, theCPU determines whether or not the vehicle SV has entered into a new areaARj (that is the present area ARj).

When the present area ARj is the same as the previous area ARj-1, theCPU makes a “No” determination at step 415, and directly proceeds tostep 420 so as to store the present area ARj in the RAM as the previousarea ARj-1. Thereafter, the CPU proceeds to step 495 so as to terminatethe present routine tentatively.

When the CPU starts processing the present routine immediately after thevehicle SV has entered into the new area ARj, the CPU makes a “Yes”determination at step 415 following step 405 and step 410, and proceedsto step 425. At step 425, the CPU determines whether or not the value ofthe confirmation flag Xf is “1”.

When the value of the confirmation flag Xf is “1”, the CPU makes a “Yes”determination at step 425, and sequentially executes “processes of step430 and step 435” described below so as to proceed to step 440.

Step 430: the CPU increments the accumulated number of confirmationsNCj-1 for the previous area ARj-1 by “1”, and increments the accumulatednumber of determinations NDj-1 for the previous area ARj-1 by “1”.

Step 435: the CPU sets the value of the confirmation flag Xf to “0”.

Whereas, if the value of the confirmation flag Xf is “0” when the CPUproceeds to step 425, the CPU makes a “No” determination at step 425,and proceeds to step 445. At step 445, the CPU increments theaccumulated number of determinations NDj-1 for the previous area ARj-1by “1”, however, the CPU does not change the accumulated number ofconfirmations NCj-1 for the previous area ARj-1. Thereafter, the CPUproceeds to step 440.

At step 440, the CPU obtains the visual check probability Prj-1 (%) forthe previous area ARj-1 by multiplying a “value (=NCj-1/NDj-1) obtainedby dividing the accumulated number of confirmations NCj-1 by theaccumulated number of determinations NDj-1” by 100 (i.e.,Prj-1=100·(NCj-1/NDj-1)). Subsequently, the CPU proceeds to step 450 soas to store the visual check probability Prj-1 in the visual checkprobability database 60 b while associating/correlating the visual checkprobability Prj-1 with the previous area ARj-1. In other words, the CPUupdates (produces) the visual check probability database 60 b by settingthe “visual check probability corresponding to the area ARj-1 stored inthe visual check probability database 60 b” to the visual checkprobability Prj-1 obtained at step 440. Thereafter, the CPU executes theprocess of step 420, and proceeds to step 495 so as to terminate thepresent routine tentatively.

When an appropriate time comes, the CPU starts process of step 500 shownin FIG. 5 (so as to execute processes for performing the automaticcleaning), and sequentially executes “processes of step 505 and step525” described below so as to proceed to step 530.

Step 505: the CPU obtains the position information (i.e., vehicleposition information) of the vehicle SV at the present time point fromthe position information obtaining device 14.

Step 510: the CPU identifies/specifies the area ARj (in which thevehicle SV is traveling) that includes a “position of the vehicle SV atthe present time point” indicated by the position information obtainedat step 505 by searching the visual check probability database 60 b.

Step 515: the CPU reads out (obtains) the visual check probability Prjcorresponding to the identified area ARj from the visual checkprobability database 60 b.

Step 520: the CPU obtains (sets) the cleaning threshold th by applyingthe visual check probability Prj obtained at step 515 to a first map Map1 (refer to FIG. 5) that is a look-up table stored in the ROM. Accordingto the first map Map 1, the cleaning threshold th is obtained in such amanner that the cleaning threshold th becomes greater as the visualcheck probability Prj becomes higher. In other words, according to thefirst map Map 1, the cleaning threshold th of when the visual checkprobability Prj is a particular value Prs is greater than the cleaningthreshold th of when the visual check probability Prj is a value smallerthan that particular value Prs.

Step 525: the CPU identifies the camera sensor whose detecting surfacepart is not being cleaned by the automatic cleaning. More specifically,the CPU identifies the camera sensor corresponding to the pump that isnot being driven among the first pump 40 and the second pump 50.

When the CPU proceeds to step 530, the CPU determines whether or not thedirty degree indicating value of the thus identified camera sensor isgreater than the cleaning threshold th. If both of the front camera 11and the second camera 12 are identified at step 525 as the camera sensorhaving the detecting surface part that is not being cleaned by theautomatic cleaning, the CPU determines whether or not the dirty degreeindicating value of the front camera 11 is greater than the cleaningthreshold th, and determines whether or not the dirty degree indicatingvalue of the rear camera 12 is greater than the cleaning threshold th,at step 530. It should be noted that the CPU calculates (obtains throughcalculation) the dirty degree indicating value of the front camera 11and the dirty degree indicating value of the rear camera 12, throughexecuting an unillustrated routine every time a predetermined timeelapses. However, the CPU stops calculating the dirty degree indicatingvalue of the front camera 11 while the first pump 40 is being driven(i.e., during the execution of the automatic cleaning for the frontcamera 11). The CPU stops calculating the dirty degree indicating valueof the rear camera 12 while the second pump 50 is being driven (i.e.,during the execution of the automatic cleaning for the rear camera 12).

When there is at least one camera sensor whose dirty degree indicatingvalue is larger than the cleaning threshold th, the CPU makes a “Yes”determination at step 530, and proceeds to step 535. At step 535, theCPU executes a process for driving the pump (the first pump 40 and/orthe second pump 50) corresponding to the camera sensor whose dirtydegree indicating value is determined to be larger than the cleaningthreshold th for a predetermined time length. Namely, the CPU cleans (orexecutes the automatic clean process for) the detecting surface part ofthe camera sensor whose dirty degree indicating value is determined tobe larger than the cleaning threshold th. Thereafter, the CPU proceedsto step 595 so as to terminate the present routine tentatively.

Whereas, when there is no camera sensor whose dirty degree indicatingvalue is larger than the cleaning threshold th, the CPU makes a “No”determination at step 530, and proceeds to step 595 so as to terminatethe present routine tentatively.

An example of the operation of the thus configured first cleaningapparatus will be described with reference to FIG. 6. In the exampleshown in FIG. 6, the visual check probability Prj corresponding to eachof the areas ARj included in a section (straight section) between apoint P0 and a point P1 is 10%. Therefore, while the vehicle SV istraveling in the section between the point P0 and the point P1, thecleaning threshold th is set at 3% that corresponds to the visual checkprobability Prj of 10%.

In the example shown in FIG. 6, while the vehicle SV is traveling in asection (a section leading to (or before) an intersection) between thepoint P1 and a point P2, the visual check probability Prj becomes higheras the vehicle SV comes closer to the point P2. Therefore, while thevehicle SV is traveling from the point P1 to the point P2, the cleaningthreshold th increases from 3% to 90%.

In addition, in the example shown in FIG. 6, the visual checkprobability Prj corresponding to each of the areas ARj included in asection (intersection section) between the point P2 and a point P3 is100%. Therefore, while the vehicle SV is traveling in the sectionbetween the point P2 and the point P3, the cleaning threshold th ismaintained at 90%.

Therefore, as understood from this example, the cleaning threshold thbecomes greater, as the vehicle SV comes closer to the intersection thatincludes the areas ARj in each of which the visual check probability Prjis high. Accordingly, a possibility that the detecting surface part ofthe camera sensor is automatically cleaned by the automatic cleanprocess becomes lower, as the vehicle SV comes closer to theintersection.

As has been described above, according to the first cleaning apparatus,a “possibility that the automatic clean process is executed when thevehicle SV is traveling in the areas ARj in each of which the visualcheck probability Prj is low” can be made high. Whereas, according tothe first cleaning apparatus, a “possibility that the automatic cleanprocess is executed when the vehicle SV is traveling in the areas ARj ineach of which the visual check probability Prj is high” can be made low.Accordingly, when the vehicle SV is present in the areas ARj in each ofwhich a “possibility that the driver visually checks the surroundingimage displayed on the display so as to monitor/check the vehiclesurroundings” is high, the automatic clean process is unlikely to beexecuted, and thus, a clear surrounding image can be displayed on thedisplay.

<<Modification of the First Embodiment>>

The present modification is different from the first embodiment only inthat the present modification updates the accumulated number ofdeterminations NDj, the accumulated number of confirmations NCj, and thevisual check probability Prj, every time a predetermined time elapses.More specifically, a CPU of the present modification executes routinesshown by flowcharts illustrated in “FIG. 7 in place of FIG. 3” and in“FIG. 8 in place of FIG. 4”.

Accordingly, when an appropriate time comes, the CPU starts process ofstep 700 shown in FIG. 7. Processes executed at step 705, step 710, step715, and step 720 shown in FIG. 7 are the same as ones executed at step305, step 310, step 315, and step 320 shown in FIG. 3, respectively.When the CPU makes a “No” determination at step 710 (i.e., when it isdetermined that the driver is not looking at the display), the CPUproceeds to step 725 so as to set the value of the confirmation flag Xfto “0”. Thereafter, the CPU proceeds to step 720.

The CPU starts process of step 800 shown in FIG. 8 after executing theroutine shown in FIG. 7, and sequentially executes “the process of step805 that is the same as one of step 405” and “the process of step 810that is the same as one of step 410” so as to proceed to step 825. Atstep 825, the CPU determines whether the value of the confirmation flagXf is “1”.

When the value of the confirmation flag Xf is “1”, the CPU makes a “Yes”determination at step 825, and proceeds to step 830. At step 830, theCPU increments the accumulated number of confirmations NCj for thepresent area ARj identified at step 810 by “1”, and increments theaccumulated number of determinations NDj for the present area ARjidentified at step 810 by “1”. Thereafter, the CPU proceeds to step 840.

Whereas, if the value of the confirmation flag Xf is “0” when the CPUproceeds to step 825, the CPU makes a “No” determination at step 825,and proceeds to step 845. At step 845, the CPU increments theaccumulated number of determinations NDj for the present area ARjidentified at step 810 by “1”, however, the CPU does not change theaccumulated number of confirmations NCj for the present area ARjidentified at step 810. Thereafter, the CPU proceeds to step 840.

At step 840, the CPU obtains the visual check probability Prj (%) forthe present area ARj by multiplying a “value (=NCj/NDj) obtained bydividing the accumulated number of confirmations NCj by the accumulatednumber of determinations NDj” by 100 (i.e., Prj=100·(NCj/NDj)).Subsequently, the CPU proceeds to step 850 so as to store the visualcheck probability Prj in the visual check probability database 60 bwhile associating/correlating the visual check probability Prj with thepresent area ARj. In other words, the CPU updates (produces) the visualcheck probability database 60 b by setting the “visual check probabilitycorresponding to the area ARj stored in the visual check probabilitydatabase 60 b” to the visual check probability Prj obtained at step 840.Thereafter, the CPU proceeds to step 895 so as to terminate the presentroutine tentatively.

As has been described above, the present modification does not updateany one of the accumulated number of confirmations NCj, the accumulatednumber of determinations NDj, and the visual check probability Prj, whenthe vehicle has entered the new area ARj. Instead, the presentmodification updates the accumulated number of confirmations NCj, theaccumulated number of determinations NDj, and the visual checkprobability Prj, every time the determination (visual checkdetermination) as to whether or not the driver is looking at the displayis made. In other words, the visual check probability database 60 b isupdated every time the predetermined time elapses. Accordingly, thepresent modification can update the visual check probability Prjappropriately.

Second Embodiment

An on-board sensor cleaning apparatus (hereinafter, sometimes referredto as a “second cleaning apparatus”) according to a second embodiment ofthe present disclosure is different from the first cleaning apparatusonly in the following points.

A second Map2 that is a look-up table shown in FIG. 9A and a third Map3that is a look-up table shown in FIG. 9B have been stored in the ROM ofthe ECU 10, in place of the first map Map1.

The ECU 10 obtains the cleaning threshold th using (based on) the secondmap Map2, when the visual check probability Prj is apt to become higherwhile the vehicle SV is traveling (or owing to changes in the area Arj).Whereas, the ECU 10 obtains the cleaning threshold th using (based on)the second map Map3, when the visual check probability Prj is not apt tobecome higher while the vehicle SV is traveling (or owing to changes inthe area Arj).

Hereinafter, these differences will be described mainly.

<Specific Operation>

The CPU of the ECU 10 according to the second embodiment executes theroutines shown by the flowcharts in FIGS. 3 and 4. Furthermore, the CPUexecutes a routine shown by a flowchart in FIG. 10 in place of FIG. 5,every time a predetermined time elapses. The descriptions of theroutines shown in FIGS. 3 and 4 are omitted, since they have beenalready described. The descriptions of steps among steps shown in FIG.10 that are the same as the steps shown in FIG. 5 are also omitted.

The CPU starts process of step 1000 shown in FIG. 10, and sequentiallyexecutes the “processes from step 505 to step 515”. Subsequently, theCPU proceeds to step 1005 so as to obtain a parameter (hereinafter,referred as a “change tendency parameter”) indicating a tendency ofchanges in the visual check probability Prj.

More specifically, the CPU calculates (obtains through calculation) achange amount dPj of the visual check probability Prj in accordance withthe following equation, every time an area where the vehicle SV istraveling changes from the previous area ARj-1 to the new (present) areaARj, by executing an unillustrated routine.

dPj=(visual check probability Prj)−(visual check probability Prj-1)

In the above equation,

the visual check probability Prj is the visual check probability Prjcorresponding to the new area ARj and stored in the visual checkprobability database 60 b; and

the visual check probability Prj-1 is the visual check probability Prj-1corresponding to the previous area ARj-1 and stored in the visual checkprobability database 60 b.

The CPU stores the thus obtained change amount dPj in the RAM as apresent change amount dP(n).

In addition, at step 1005, the CPU reads out a one-time previous changeamount dP(n-1) and a two-time previous change amount dP(n-2). Theone-time previous change amount dP(n-1) is the change amount of thevisual check probability obtained when the area where the vehicle SV wastraveling changed from the area ARj-2 to the area ARj-1. The tow-timeprevious change amount dP(n-2) is the change amount of the visual checkprobability obtained when the area where the vehicle SV was travelingchanged from the area ARj-3 to the area ARj-2.

Then, the CPU obtains, as the change tendency parameter K, an averagevalue among the change amounts dP(n), dP(n-1), and dP(n-2) (i.e.,K=(dP(n)+dP(n-1)+dP(n-2))/3). It should be noted that the number of thechange amounts used to obtain the change tendency parameter K may beone, however, is more preferably two or more.

Subsequently, the CPU proceeds to step 1010 so as to determine whetheror not the change tendency parameter K is equal to or greater than apositive predetermined value Kth in order to determine whether or notthe visual check probability Prj is apt to (or tends to) become higher(rise/increase).

When the visual check probability Prj is apt to (or tends to) becomehigher (i.e., when the change tendency parameter K is equal to orgreater than the value Kth), the CPU makes a “Yes” determination at step1010, and proceeds to step 1015. At step 1015, the CPU applies thevisual check probability Prj obtained at step 515 shown in FIG. 10 tothe second map Map2 (refer to a solid line a1) shown in FIG. 9A so as todetermine (obtain/set) the cleaning threshold th.

According to the second map Map2, the cleaning threshold th ismaintained at a constant first threshold th1 when the visual checkprobability Prj is equal to or higher than “0” and is equal to or lowerthan a first probability Pr1 (namely, when the visual check probabilityPrj is in a first probability range RP1 between 0 and Pr1). It ispreferable that the first probability Pr1 be a value equal to or higherthan 20% and equal to or lower than 35%. In the present example, thefirst probability Pr1 is 35%. It is preferable that the first thresholdth1 be a value equal to or higher than 10% and equal to or lower than50% from a viewpoint of reducing the consumed amount of the cleaningfluid. In the present example, the first threshold th1 is 40%.

Furthermore, according to the second map Map2, the cleaning threshold this maintained at a constant second threshold th2 when the visual checkprobability Prj is higher than the first probability Pr1 and is lowerthan a second probability Pr2 (namely, when the visual check probabilityPrj is in a second probability range RP2 between Pr1 and Pr2). Thesecond probability Pr2 is higher than the first probability Pr1, and itis preferable that the second probability Pr2 be a value equal to orhigher than 25% and equal to or lower than 50%. In the present example,the second probability Pr2 is 50%. The second threshold th2 is smallerthan the first threshold th1, and is 3% in the present example.

In addition, according to the second map Map2, the cleaning threshold this set to a value that becomes greater within a range that is largerthan the first threshold th1 and is equal to or smaller than a thirdthreshold th3 as the visual check probability Prj becomes higher, whenthe visual check probability Prj is equal to or higher than the secondprobability Pr2 and is equal to or lower than 100% (namely, when thevisual check probability Prj is in a third probability range RP3 betweenPr2 and 100%). It is preferable that the third threshold th3 is equal toor greater than 80% and is equal to or smaller than 95%. In the presentexample, the third threshold th3 is 90%.

As understood from the above, when the visual check probability Prj isin the second probability range RP2, the cleaning threshold th is set ata relatively small value (i.e., the second threshold th2) in the casewhere the visual check probability Prj is apt to increase, as comparedto the case where the visual check probability Prj is not apt toincrease (refer to FIG. 9B). Thus, when the visual check probability Prjis in the second probability range RP2 and is apt to increase, thechances that the automatic cleaning process is executed are great.

After executing the process of step 1015 shown in FIG. 10, the CPUexecutes some of the processes of step 525 to step 535, as describedabove, and then, proceeds to step 1095 so as to terminate the presentroutine tentatively.

In contrast, when the visual check probability Prj is not apt to (ortend to) become higher (i.e., when the change tendency parameter K issmaller than the value Kth), the CPU makes a “No” determination at step1010, and proceeds to step 1020. At step 1020, the CPU applies thevisual check probability Prj obtained at step 515 shown in FIG. 10 tothe third map Map3 (refer to a solid line b1) shown in FIG. 9B so as todetermine (obtain) the cleaning threshold th.

The third map Map3 is different from the second map Map2 only in thatthe third map Map3 sets the cleaning threshold th to the first thresholdth1 when the visual check probability Prj is in the second probabilityrange RP2. Accordingly, even when the visual check probability Prj is inthe second probability range RP2, the cleaning threshold th is not setat the second threshold th2 that is relatively small, but is set at thefirst threshold th1, in the case where the visual check probability Prjis not apt to increase.

After executing the process of step 1020, the CPU executes some of theprocesses of step 525 to step 535, as described above, and then,proceeds to step 1095 so as to terminate the present routinetentatively.

An example of the operation of the thus configured second cleaningapparatus will be described with reference to FIG. 11. In the exampleshown in FIG. 11, when the vehicle SV is traveling in a section betweena point P0 and a point P1, the visual check probability Prj is constantand thus does not increase. Therefore, in this case, the cleaningthreshold th is set at the first threshold th1 (=40%) based on the thirdmap Map3. In the example, when the vehicle SV is traveling in a sectionbetween the point P1 and a point P2, the visual check probability Prj isdetermined to be apt to increase. Therefore, in this case, the cleaningthreshold th is set/obtained based on the second map Map2. Especially,when the vehicle SV is traveling in a section between a point P1 a and apoint P1 b, the visual check probability Prj is higher than the firstprobability Pr1 and is lower than the second probability Pr2, andtherefore, the cleaning threshold th is set at 3% that is the secondthreshold th2. Accordingly, the chances that the automatic cleaningprocess is executed are great in the section between the point P1 a andthe point P1 b. Subsequently, when the visual check probability Prj doesnot increase (namely, when the vehicle SV is traveling in a sectionbetween the point P2 and a point P3), the cleaning threshold th is setbased on the third map Map 3.

As has been described above, according to the second cleaning apparatus,when it is determined that the visual check probability Prj is not aptto increase, the cleaning threshold th is kept at a relatively greatvalue (e.g., 40%), and thus, a frequency that the automatic cleanprocess is executed becomes low. Accordingly, in this case, the consumedamount of the cleaning fluid can be reduced. In addition, according tothe second cleaning apparatus, when it is determined that the visualcheck probability Prj is apt to increase, the cleaning threshold th isset to the second threshold th2 that is the extremely small value (e.g.,3%) in a period before the visual check probability Prj becomes veryhigh (i.e., in a period in which the visual check probability Prj ishigher than the first probability Pr1 and is lower than the secondprobability Pr2). Accordingly, the automatic cleaning process canoften/easily be executed in a period before the visual check probabilityPrj is likely to become very high. Furthermore, when the visual checkprobability Prj is very high, the cleaning threshold th is set at thethird threshold th3 (e.g., 90%) that is extremely high. Therefore, inthis case, the chances that the automatic cleaning process is executedare lowered.

Third Embodiment

Similarly to the first cleaning apparatus, an on-board sensor cleaningapparatus (hereinafter, sometimes referred to as a “third cleaningapparatus”) according to a third embodiment of the present disclosuresets the cleaning threshold th in such a manner that the cleaningthreshold th becomes greater as the visual check probability Prj becomeshigher. Note, however, the third cleaning apparatus is different fromthe first cleaning apparatus only in that the third cleaning apparatussets the cleaning threshold th at a maximum value so that the automaticcleaning process is prevented from starting and stops the automaticcleaning process that is being executed, while it is determined that thedriver is looking at the display. In other words, the third cleaningapparatus prohibits executing the automatic cleaning process, while itis determined that the driver is looking at the display.

<Specific Operation>

The CPU of the ECU 10 according to the third embodiment executes theroutines shown by the flowcharts in FIGS. 7 and 8. Furthermore, the CPUexecutes a routine shown by a flowchart in FIG. 12 in place of FIG. 5,every time a predetermined time elapses. The descriptions of theroutines shown in FIGS. 7 and 8 are omitted, since they have beenalready described. The descriptions of steps among steps shown in FIG.12 that are the same as the steps shown in FIG. 5 are also omitted. Theroutine shown in FIG. 12 is different from the routine shown in FIG. 5only in that step 1205, step 1210, and step 1215 are added.

The CPU starts process of step 1200 shown in FIG. 12, and sequentiallyexecutes the “processes from step 505 to step 515”. Subsequently, theCPU proceeds to step 1205 so as to determine whether or not the value ofthe confirmation flag Xf is “0”.

When the value of the confirmation flag Xf is “0”, the CPU makes a “Yes”determination at step 1205, and proceeds to step 520. As describedabove, the CPU obtains (sets) the cleaning threshold th at step 520, andexecutes the processes of step 525 and steps following step 525.

Whereas, when the value of the confirmation flag Xf is “1”, the CPUmakes a “No” determination at step 1205, and executes processes of step1210 and step 1215 as described below. Thereafter, the CPU executes theprocesses of step 525 and steps following step 525.

Step 1210: the CPU sets the cleaning threshold th at the maximum value(i.e., 100% in this example) corresponding to the maximum value of thedirty degree indicating value. This prohibits the CPU from making a“Yes” determination at step 530, and therefore, executing the automaticcleaning process does not start (or is prohibited).

Step 1215: when there is a camera sensor whose detecting surface part isbeing cleaned by the automatic cleaning (and/or by a manual cleaningbased on an operation to an unillustrated manual switch), the CPU stopscleaning for the camera sensor (prohibits the cleaning process). Morespecifically, the CPU stops driving the first pump 40 if the first pump40 is being driven, and the CPU stops driving the second pump 50 if thesecond pump 50 is being driven.

An example of the operation of the thus configured third cleaningapparatus will be described with reference to FIG. 13. It should benoted that the visual check probability Prj and the cleaning thresholdth are drawn in such a manner that they continuously change, forsimplicity. In the example shown in FIG. 13, it is determined that thedriver is not looking at the display (namely, confirmation flag Xf=0),when the vehicle SV drives in any of a section between a point P0 and apoint P1 d, a section between a point P1 e and a point P2 a, and asection between a point P2 b and a point P2 c. Accordingly, when thevehicle SV is traveling in these sections, the third cleaning apparatusoperates similarly to the first cleaning apparatus.

Whereas, it is determined that the driver is looking at the display(namely, confirmation flag Xf=1), when the vehicle SV drives in any of asection between the point P1 d and the point P1 e, a section between thepoint P2 a and the point P2 b, and a section between the point P2 c anda point P3. Accordingly, when the vehicle SV is traveling in thesesections, the third cleaning apparatus sets the cleaning threshold th tothe value (100% in the present example) corresponding to the maximumvalue of the dirty degree indicating value, stops driving the first pump40 to stop cleaning using the first pump 40 if the first pump 40 isbeing driven, and stops driving the second pump 50 to stop cleaningusing the second pump 50 if the second pump 50 is being driven.

According to the third cleaning apparatus, the automatic cleaning forthe camera sensor is not executed so that there is no injection of thecleaning fluid to the detecting surface part that would cause thesurrounding image to be blurred, while the driver is looking at thesurrounding image displayed on the display. Therefore, the driver canvisually check the “surrounding image which is not blurred” so as tomonitor/check the vehicle surroundings.

The present disclosure is not limited to the above embodiments, but mayemploy various modifications within the scope of the present disclosure.

For example, in each of the embodiments, the visual check probabilitydatabase 60 b may be arranged in a cloud 100, as shown in FIG. 14. Thecloud 100 is connected with a plurality of vehicles SV through acommunication link IN1 (e.g., an internet link) so as to be able toexchange information (data) between the cloud 100 and the vehicles.Hereinafter, each of the first to third cleaning apparatus is simplyreferred to as a “cleaning apparatus”.

The cloud 100 includes a server 101 and a storage device 102. The server101 includes a computer. The storage device 102 includes the mapinformation database 60 a and the visual check probability database 60b. The server 101 can conduct a search for specific data stored in eachof the databases in the storage device 102 and retrieve the data fromeach of the databases in the storage device 102. The server 101 can alsowrite/store data in each of the databases in the storage device 102.

The cleaning apparatus mounted on the vehicle SV includes a radiocommunication device 110. The radio communication device 110 is a radiocommunication terminal configured to exchange information with the cloud100 through the communication link IN1.

In the above system shown in FIG. 14, the CPU of the ECU 10 executes theroutine shown in FIG. 7. Note, however, the CPU executes a process fortransmitting a data set including “the value of the confirmation flag Xfand the position information associated the value of the confirmationflag Xf” to the cloud 100 using the radio communication device 110,after executing the process of step 720 show in FIG. 7.

When the server 101 has received the above-described data set from anyone of the vehicles SV, the server 101 executes the processes shown inthe routine of FIG. 8. Especially, at step 850, the server 101associates the visual check probability Prj with the area ARj, and storethe visual check probability Prj in the visual check probabilitydatabase 60 b in the cloud 100.

In addition, at step 515 in each of the routines shown in FIGS. 5, 10,and 12, the CPU of the ECU 10 transmits a data set of the present areaARj of the vehicle SV and a vehicle ID for identifying that vehicle SVto the cloud 100. When the server 101 of the cloud 100 has received thedata set of the present area ARj and the vehicle ID, the server 101reads out the visual check probability Prj corresponding to the receivedpresent area ARj from the visual check probability database 60 b.Thereafter, the server 101 transmits the thus read out visual checkprobability Prj to the vehicle identified by the received vehicle ID.The CPU of the ECU 10 of that vehicle receives the visual checkprobability Prj transmitted from the server 101 at step 515.

It should be noted that the server 101 may include the first map Map1,or a set of the second map Map2 and the third map Map3. In this case,the server 101 may determine the cleaning threshold th using these maps,in the similar way that the ECU 10 of the above-described cleaningapparatus of the embodiments does. In this configuration, the server 101transmits the cleaning threshold th to the vehicle identified by thevehicle ID. The ECU 10 of that vehicle receives the cleaning thresholdth, and executes the processes from step 525 to step 535 using the thusreceived cleaning threshold th.

Alternatively, in the case where the server 101 includes the first mapMap1, or a set of the second map Map2 and the third map Map3, anddetermines the cleaning threshold th using these maps, in the similarway that the ECU 10 of the above-described cleaning apparatus of theembodiments does, the server 101 may be configured to:

obtain, from the vehicle SV, “the vehicle ID, and either the vehicleposition information or the present area ARj” of that vehicle SV, andthe dirty degree indicating value of the camera sensor of that vehicleSV;

obtain the visual check probability Prj;

obtain (specify, determine) the cleaning threshold th based on thevisual check probability Prj;

make a determination of whether or not the dirty degree indicating valuehas become larger than the cleaning threshold th (i.e., determinewhether the automatic cleaning start condition has become satisfied);and

transmit the result of the determination to the vehicle SV identified bythe vehicle ID.

In this case, the ECU 10 of the vehicle SV executes the automatic cleanprocess when the received result of the determination indicates that theautomatic cleaning start condition has become satisfied.

The vehicle may comprise a “camera for monitoring dirty degree” that cantake an image of the detecting surface part of the camera sensor. Inthis case, the dirty degree indicating value may be obtained byanalyzing the image of the detecting surface part. Alternatively, thedirty degree indicating value may be obtained according to a knownmethod.

In the above-described embodiments, the ease of satisfaction of theautomatic cleaning start condition (how easy the automatic cleaningstart condition becomes satisfied) is varied by varying the cleaningthreshold th based on the visual check probability Prj. Alternatively,the ease of satisfaction of the automatic cleaning start condition maybe varied by correcting/varying the dirty degree indicating value basedon the visual check probability Prj. In this case, the dirty degreeindicating value is corrected/varied in such a manner that the dirtydegree indicating value becomes smaller while the cleaning threshold this maintained at a constant value, under conditions that the cleaningthreshold th becomes high in the above-described embodiments, and it isdetermined that the automatic cleaning start condition becomes satisfiedwhen the corrected dirty degree indicating value becomes greater thanthe cleaning threshold th that is maintained at the constant value.Further alternatively, the ease of satisfaction of the automaticcleaning start condition may be varied by varying both of the cleaningthreshold th and the dirty degree indicating value, based on the visualcheck probability Prj.

The above-described embodiments may be applied to another on-boardsensor cleaning apparatus configured to include an on-board sensor otherthan the camera sensor and a cleaning unit for cleaning a detectingsurface part of that another on-board sensor, and configured to displayinformation obtained based on information detected by that anotheron-board sensor on the display. Examples of the on-board sensor otherthan the camera sensor may be a sensor configured to receive “sonic waveor electromagnetic wave” that passes through a detecting surface part ofthe sensor that is exposed to the outside of the vehicle. In this case,the electromagnetic wave received by the sensor may include visiblelight, laser light, infrared light, and electrical wave in millimeterwaveband. The sonic wave received by the sensor may includeelectromagnetic wave.

The front camera 11 may be disposed on a front windshield in the side ofthe cabin of the vehicle SV, and be configured to obtain the front imagedata utilizing visible light passing through the front windshield. Inthis case, the detecting surface part of the front camera 11 is a part(window part) of the front windshield through which the visible lightpasses that is input to the front camera 11.

Similarly, the rear camera 12 may be disposed on a rear glass in theside of the cabin of the vehicle SV, and be configured to obtain therear image data utilizing visible light passing through the rear glass.In this case, the detecting surface part of the rear camera 12 is a part(window part) of the rear glass through which the visible light passesthat is input to the rear camera 12.

What is claimed is:
 1. An on-board sensor cleaning apparatus, applied toa vehicle including an on-board sensor configured to obtain informationrepresenting surroundings of said vehicle based on electromagnetic waveor sonic wave which passes through a detecting surface part exposed tooutside of said vehicle and a display device configured to display animage or displayed information produced based on said informationobtained by said on-board sensor, comprising: a cleaning unit configuredto perform a cleaning process to clean said detecting surface part ofsaid on-board sensor using cleaning fluid; a position informationobtaining device configured to obtain vehicle position informationindicating a position of said vehicle; and a control unit configured to:obtain a result of a determination of whether or not an automaticcleaning start condition is satisfied, wherein said determination ismade, using a storage device which has stored a piece of area positioninformation capable of identifying a position of each of predeterminedareas on a ground and a visual check probability correlating valuecorrelated with a visual check probability that a driver of said vehiclevisually checks said display device while said piece of area positioninformation and said visual check probability correlating value beingassociated with each other, based on said visual check probabilitycorrelating value which corresponds to one of said areas which includessaid position of said vehicle indicated by said vehicle positioninformation obtained by said position information obtaining device; andcontrol said cleaning unit in such a manner that said cleaning unitperforms said cleaning process when said result of said determinationindicates that said automatic cleaning start condition is satisfied. 2.The on-board sensor cleaning apparatus according to claim 1, wherein,said storage device is mounted on said vehicle; and said control unit isconfigured to: obtain, based on said obtained vehicle positioninformation, said visual check probability correlating valuecorresponding to one of said areas which includes said position of saidvehicle, from said storage device; and obtain said result of saiddetermination, by setting said automatic cleaning start condition basedon said obtained visual check probability correlating value, and bydetermining whether or not said automatic cleaning start conditionbecomes satisfied.
 3. The on-board sensor cleaning apparatus accordingto claim 1, further comprising a radio communication device which ismounted on said vehicle and is configured to be capable of communicatingwith an information-processing equipment which is located outside ofsaid vehicle and which includes said storage device, wherein, saidcontrol unit is configured to: obtain, based on said obtained vehicleposition information, said visual check probability correlating valuecorresponding to one of said areas which includes said position of saidvehicle, from said storage device, by communicating with saidinformation-processing equipment using said radio communication device;and obtain said result of said determination, by setting said automaticcleaning start condition based on said obtained visual check probabilitycorrelating value, and by determining whether or not said automaticcleaning start condition becomes satisfied.
 4. The on-board sensorcleaning apparatus according to claim 2, wherein, said on-board sensoris a camera sensor which is configured to take a picture of saidsurroundings of said vehicle using light as said electromagnetic wave toobtain image information as said information representing saidsurroundings of said vehicle; and said control unit is configured to:obtain, based on said image information, a dirty degree indicating valueindicating a degree of dirtiness of said detecting surface part of saidon-board sensor; and determine whether or not said automatic cleaningstart condition becomes satisfied by comparing said dirty degreeindicating value and a cleaning threshold, and wherein, said controlunit is configured to: set said cleaning threshold based on saidobtained visual check probability correlating value so as to set saidautomatic cleaning start condition; and obtain said result of saiddetermination which is indicating that said automatic cleaning startcondition has become satisfied when said dirty degree indicating valueis larger than said cleaning threshold.
 5. The on-board sensor cleaningapparatus according to claim 4, wherein, said control unit is configuredto vary said cleaning threshold in such a manner that said cleaningthreshold is greater when said obtained visual check probabilitycorrelating value is a specific value than when said obtained visualcheck probability correlating value is smaller than said specific value,so as to set said automatic cleaning start condition.
 6. The on-boardsensor cleaning apparatus according to claim 4, wherein, said controlunit is configured to vary said cleaning threshold so as to set saidautomatic cleaning start condition in such a manner that: said cleaningthreshold is equal to a first threshold when said obtained visual checkprobability correlating value is in a first range that is equal to orsmaller than a first visual check probability correlating value; andsaid cleaning threshold is equal to a second threshold smaller than saidfirst threshold when said obtained visual check probability correlatingvalue is in a second range that is larger than said first visual checkprobability correlating value and smaller than a second visual checkprobability correlating value, and a change in said visual checkprobability correlating value indicates a tendency that said visualcheck probability correlating value is increasing.
 7. The on-boardsensor cleaning apparatus according to claim 1, further comprising adriver's information obtaining device configured to obtain driver'sinformation that is used for determining a state of said driver,wherein, said control unit is configured to: prohibit executing saidcleaning process while it is determined, based on said driver'sinformation, that said driver is visually checking said display device.8. The on-board sensor cleaning apparatus according to claim 1, furthercomprising a driver's information obtaining device configured to obtaindriver's information that is used for determining a state of saiddriver, wherein, said control unit is configured to: make avisually-check-determination as to whether or not said driver hasvisually checked said display device, based on said driver'sinformation; identify one of said areas that includes a position atwhich a result of said visually-check-determination is obtained;calculate said visual check probability correlating value for saididentified one of said areas, based on said result of saidvisually-check-determination; and store said calculated visual checkprobability correlating value in said storage device while associatingsaid calculated visual check probability correlating value with saidarea position information indicating said identified one of said areas.9. An on-board sensor cleaning method, applied to a vehicle including:an on-board sensor configured to obtain information representingsurroundings of said vehicle based on electromagnetic wave or sonic wavewhich passes through a detecting surface part exposed to outside of saidvehicle; a display device configured to display an image or displayedinformation produced based on said information obtained by said on-boardsensor; a cleaning unit configured to perform a cleaning process toclean said detecting surface part of said on-board sensor using cleaningfluid; and a position information obtaining device configured to obtainvehicle position information indicating a position of said vehicle,comprising: a step of obtaining a visual check probability correlatingvalue corresponding to one of areas which includes a position of saidvehicle indicated by said vehicle position information, using a storagedevice which has stored a piece of area position information capable ofidentifying a position of each of predetermined areas on a ground and avisual check probability correlating value correlated with a visualcheck probability that a driver of said vehicle visually checks saiddisplay device while said piece of area position information and saidvisual check probability correlating value being associated with eachother; a step of setting an automatic cleaning start condition based onsaid obtained visual check probability correlating value; a step ofobtaining a result of a determination of whether or not said automaticcleaning start condition becomes satisfied; and a step of controllingsaid cleaning unit in such a manner that said cleaning unit performssaid cleaning process when said result of said determination indicatesthat said automatic cleaning start condition is satisfied.
 10. Theon-board sensor cleaning method according to claim 9, furthercomprising: a step of obtaining driver's information that is used fordetermining a state of said driver; a step of making avisually-check-determination as to whether or not said driver hasvisually checked said display device, based on said driver'sinformation, and of identifying one of said areas that includes aposition at which a result of said visually-check-determination isobtained; a step of calculating said visual check probabilitycorrelating value for said identified one of said areas, based on saidresult of said visually-check-determination; and a step of storing saidcalculated visual check probability correlating value in said storagedevice while associating said calculated visual check probabilitycorrelating value with said area position information indicating saididentified one of said areas.
 11. The on-board sensor cleaning apparatusaccording to claim 3, wherein, said on-board sensor is a camera sensorwhich is configured to take a picture of said surroundings of saidvehicle using light as said electromagnetic wave to obtain imageinformation as said information representing said surroundings of saidvehicle; and said control unit is configured to: obtain, based on saidimage information, a dirty degree indicating value indicating a degreeof dirtiness of said detecting surface part of said on-board sensor; anddetermine whether or not said automatic cleaning start condition becomessatisfied by comparing said dirty degree indicating value and a cleaningthreshold, and wherein, said control unit is configured to: sett saidcleaning threshold based on said obtained visual check probabilitycorrelating value so as to set said automatic cleaning start condition;and obtain said result of said determination which is indicating thatsaid automatic cleaning start condition has become satisfied when saiddirty degree indicating value is larger than said cleaning threshold.12. The on-board sensor cleaning apparatus according to claim 11,wherein, said control unit is configured to vary said cleaning thresholdin such a manner that said cleaning threshold is greater when saidobtained visual check probability correlating value is a specific valuethan when said obtained visual check probability correlating value issmaller than said specific value, so as to set said automatic cleaningstart condition.
 13. The on-board sensor cleaning apparatus according toclaim 11, wherein, said control unit is configured to vary said cleaningthreshold so as to set said automatic cleaning start condition in such amanner that: said cleaning threshold is equal to a first threshold whensaid obtained visual check probability correlating value is in a firstrange that is equal to or smaller than a first visual check probabilitycorrelating value; and said cleaning threshold is equal to a secondthreshold smaller than said first threshold when said obtained visualcheck probability correlating value is in a second range that is largerthan said first visual check probability correlating value and smallerthan a second visual check probability correlating value, and a changein said visual check probability correlating value indicates a tendencythat said visual check probability correlating value is increasing.